There are a variety of containers available for enabling controlled dispensing of the liquid content thereof through an outlet, the outlet having associated with it a control valve in the form of a flexible diaphragm carrying a nose or stud movable on deflection of the diaphragm between a position closing the outlet to prevent dispensing of the liquid and an open position permitting liquid to be dispensed through the outlet.
One such arrangement is disclosed in U.S. Pat. No. 5,454,494 in which the diaphragm is attached to a hollow cylindrical support element which, in turn, is located in a rigid insert positioned within the associated container and incorporating cylindrical passageways for the flow therethrough of liquid from the container to a dispensing chamber from which it can be discharged in accordance with deflection of the diaphragm resultant from pressurisation of the liquid within the container.
The assembly described in U.S. Pat. No. 5,454,494 suffers from a number of disadvantages not the least of which is that it comprises a number of components the constructions of which are relatively complex, and which are difficult to assemble.
In particular, the process of assembly is considerably complicated by the fact that the rigid insert is to be positioned within the upper regions of the container and must be inserted therein from the bottom of the container, only after which can the container be closed. Thus the described container is clearly not suited to high volume production.
Additionally, the construction of the insert is such that flow of liquid therethrough from the body of the container to the aforementioned dispensing chamber is restricted by virtue of the provision of cylindrical passageways the total cross-sectional area of which is considerably less than that of the container and/or the dispensing chamber.
It has been further proposed in U.S. Pat. No. 5,325,999 to provide an assembly which includes a compound flexible diaphragm part of which constitutes a domed control valve for opening and closing an associated outlet on deformation of the dome by pressurised liquid from the container. However, the assembly is again of relatively complex construction and is not suited to mass production.
Additionally, flow from the body of the container towards the outlet is by way of a single central passageway which imposes considerable restriction upon the rate of flow, and the nature, in particular the viscosity, of liquids that can be dispensed by the container, while the construction of the assembly is such that the outlet must be offset from the central passageway, therefore imposing restrictions on the position of the outlet from the assembly and eliminating the possibility of a centrally-located outlet which is often desirable.
DE-A1-4329808 discloses a container or tube in which liquid to be dispensed is supplied to a dispensing chamber through a pair of diametrically opposed flow openings. These openings comprise narrow cylindrical passageways the total cross-sectional area of which is again considerably less than that of the container and/or the dispensing chamber, and whereby liquid flow to the dispensing chamber is significantly restricted.
U.S. Pat. No. 2,695,119 discloses a collapsible tube which delivers liquid to a chamber in a cap for the tube by way of a plurality of narrow bores defined in an axially movable plug within the tube, dispensing of the liquid through an outlet in the cap being under the control of a valve member seating on the movable plug, the valve member defining therein an internal volume which is vented to atmosphere through an angled bore formed in the plug and aligned with, at one end, an opening in the lower wall of the valve member and, at the other end, an opening in the wall of the cap.
The overall assembly as disclosed is of complex construction, is difficult to assembly and provides for restricted flow of liquid from the tube to the chamber within the cap.
Reference is also made to U.S. Pat. No. 2,607,515 and U.S. Pat. No. 2,643,794 both of which disclose containers the constructions of which are such that manufacture and assembly thereof both pose difficulties.